President Obama was fighting critics on two fronts during his G20 speech in Turkey on Monday.

President Obama was fighting critics on two fronts Monday, pushing back against politicians who questioned how the White House vetted Syrian refugees and giving a smackdown to those who think his ISIS battle plan is too weak.

"When I hear folks say that, well, maybe we should just admit the Christians but not the Muslims, when I hear political leaders suggesting that there would be a religious test for which person who's fleeing from a war-torn country is admitted, when some of those folks themselves come from families who benefited from protection when they were fleeing political persecution, that's shameful," the President added.

"As I listen to those who suggest something else needs to be done, typically the things they suggest need to be done are things that we are already doing. The one exception is that there had been a few who suggested that we should put large numbers of U.S. troops on the ground," Obama said.

"And it is not just my view, but the view of my closest military and civilian advisers, that that would be a mistake," he added.

"When we send troops in, those troops get injured, they get killed, they're away from their families. Our country spends hundreds of billions of dollars. And so, given the fact that there are enormous sacrifices involved in any military action, it's best that we don't, you know, shoot first and aim later," he said.

Victims of the Paris terror attacks

The Republican governors of Iowa, Indiana, Louisiana, Michigan and Massachusetts — and the Democratic governor of Pennsylvania — all said they want more information from the White House on the program.

In addition, the GOP governors of Texas, Mississippi, Alabama and Arkansas said they would refuse to accept Syrian refugees.

Three New York Republican politicians also waded into the debate.

Calling the refugee crisis a "Trojan horse scenario" that allows terrorists entry to the U.S., state Sen. Thomas Croci (R-Suffolk County) urged Gov. Cuomo to support legislation to create a "terrorist registry."

"It is the height of naivete, and ignores the lessons of Sept. 11, to admit refugees from Syria and other Middle Eastern nations to America, and to New York, without more extensive vetting than is now taking place," Croci said.

He spoke out in favor of Obama's decision to admit additional asylum-seekers, noting that there were ways to do it safely while meeting America's humanitarian obligations.

"We have the ability to identify 10,000 who do have information that can be collaborated, fingerprints, passports, birth records. ... I would hope, from my perspective, that we would basically take those who have the documentation," Bratton said.

A UN official warned against any backlash against migrants in Europe.

"One cannot conceive of a European continent which is going to thrive economically if borders are ... fenced off with walls and barbed wire and machine gun nests and observation towers," said Zeid Raad al-Hussein, UN High Commissioner for Human Rights, at a New York event Monday night.